Thin-film magnetic head and method of making the same

ABSTRACT

The method of making a thin-film magnetic head in accordance with the present invention forms a cover layer on an insulating layer about a magnetoresistive film so as to eliminate a protrusion riding on the magnetoresistive film. Then, the protrusion can be eliminated by etching. The part of insulating layer clad with the cover layer is not etched. This can prevent short-circuit from occurring because of thinning the insulating layer.

BACKGROUND OF THE INVENTION

[0001] 1. Field of the Invention

[0002] The present invention relates to a method of making a thin-filmmagnetic head, a method of making a head gimbal assembly, a method ofmaking a hard disk drive, and a thin-film magnetic head.

[0003] 2. Related Background Art

[0004] In general, for yielding a magnetoresistive film such as TMR(Tunneling MagnetoResistive) film, a resist layer is initially formed ona magnetic layer formed on a lower shield layer, and then, using theresist layer as a mask, the magnetic layer is etched so as to be formedinto a magnetoresistive film having a desirable pattern. Further, aninsulating layer for insulating the lower shield layer and an uppershield layer, which will be formed later, from each other is formedabout thus obtained magnetoresistive film (as disclosed in JapanesePatent Application Laid-Open No. HEI 11-191206, for example).

SUMMARY OF THE INVENTION

[0005] However, the inventors have found that there is a fear of theupper shield layer and the magnetoresistive film short-circuitingtherebetween. The reason will be explained with reference to theconventional manufacturing process shown in FIGS. 8A to 8C and 9A to 9C.

[0006] First, as shown in FIG. 8A, a magnetic layer 110 to become a TMRfilm (magnetoresistive film) is formed on a lower shield layer 101, anda resist layer 120 is formed on the magnetic layer 110. Subsequently,using the resist layer 120 as a mask, ion-milling is carried out, suchthat the magnetic layer 110 is patterned into a TMR film 130 having adesirable pattern. FIG. 8B and the drawings subsequent thereto show onlythe part on the right side of a dash-single-dot line 1 in FIG. 8A.

[0007] Then, as shown in FIG. 8C, an insulating layer 121 such as Al₂O₃is formed by sputtering or the like, so as to secure insulation aboutthe TMR film 130. Here, an insulating layer 131 is deposited on theresist layer 120 in addition to that surrounding the TMR film 130. Also,under the influence of the incident angle of particles at the time ofsputtering and the like, a protrusion 121 a riding on the TMR film 130is formed. Further, a depression 121 b depressed as a shadow of theresist layer (by so-called shadow effect) is formed between theprotrusion 121 a and a flat part 121 c.

[0008] Next, as shown in FIG. 9A, liftoff is carried out, so as toremove the resist layer 120 together with the insulating layer 131deposited thereon. This drawing shows the state after the liftoff. Asdepicted, the protrusion 121 a still remains in the insulating layer121. The protrusion 121 a may block current paths of the TMR 130, and soforth, and thus is preferably removed. Therefore, as shown in FIG. 9B,the protrusion 121 a on the TMR film 130 is removed by wet etching, forexample. Thereafter, as shown in FIG. 9C, an upper shield layer 140 isformed by sputtering or the like, for example, so as to complete areproducing section of a thin-film magnetic head.

[0009] In thus manufactured thin-film magnetic head, however, thedepression 121 b may become deeper when removing the protrusion 121 a bywet etching in the step of FIG. 9B, thereby causing the upper shieldlayer 140 and the TMR film 130 to short-circuit therebetween.

[0010] For overcoming the problem mentioned above, it is an object ofthe present invention to provide a method of making a thin-film magnetichead, a method of making a head gimbal assembly, a method of making ahard disk drive, and a thin-film magnetic head which can eliminate aprotrusion riding on a magnetoresistive film in an insulating layerformed about the magnetoresistive film while preventing short-circuitfrom occurring because of thus thinned insulating layer.

[0011] The present invention provides a method of making a thin-filmmagnetic head comprising a magnetoresistive film, the method comprisingthe steps of forming a magnetic layer to become the magnetoresistivefilm; forming a resist layer on an upper side of the magnetic layer;patterning the magnetic layer while using the resist layer as a mask soas to yield the magnetoresistive film; laminating an insulating layerabout the magnetoresistive film; forming a cover layer on the insulatinglayer so as to exclude a protrusion riding on the magnetoresistive filmin the insulating layer; and etching the insulating layer formed withthe cover layer so as to eliminate the protrusion.

[0012] In the method of making a thin-film magnetic head in accordancewith the present invention, the protrusion riding on themagnetoresistive film can be removed by etching. Also, since theinsulating layer surrounding the magnetoresistive film is formed withthe cover layer so as to exclude the protrusion, the part clad with thecover layer in the insulating layer is not etched. This can preventshort-circuit from occurring because of thinning the insulating layer.

[0013] Preferably, in the method of the present invention, a particleforming the cover layer has a greater incident angle with respect to asurface direction of the magnetoresistive film than an incident angle ofa particle forming the insulating layer with respect to the surfacedirection of the magnetoresistive film.

[0014] When forming the insulating layer about the magnetoresistivefilm, the resist layer is disposed on the magnetoresistive film asmentioned above. If the insulating layer is formed by sputtering in thisstate, a depression acting as a shadow of the resist layer appears(so-called shadow effect). As the depression is shallower, theoccurrence of short-circuit is suppressed more effectively. Therefore,sputtering particles are made incident on the magnetoresistive filmwhile being inclined with respect to a normal of the magnetoresistivefilm. Making particles obliquely incident on the lower side of theresist layer as such becomes a cause of forming the protrusion.Subsequently, when forming the cover layer by sputtering, the incidentangle of particles with respect to the surface direction of themagnetoresistive film is made greater than that at the time of formingthe insulating layer as mentioned above. Namely, the particle incidentangle is closer to the normal of the magnetoresistive film when formingthe cover layer than when forming the insulating layer. As a result, thecover layer can easily be formed so as to exclude the protrusion.

[0015] Preferably, in the present invention, the magnetoresistive filmis configured such that a sense current flows in a layer thicknessdirection. When the thin-film magnetic head has a so-called CPP (CurrentPerpendicular to Plane) structure in which the sense current flows inthe film thickness direction as such, the insulating layer riding on themagnetoresistive film blocks the current. When the present invention isemployed in a thin-film magnetic head having a CPP structure, the sensecurrent flows favorably, whereby magnetic information reproducingperformances can be improved.

[0016] The cover layer may be formed by SiO₂ or AlN. The cover layer mayalso be formed by a metal selected from the group consisting of Ta, Cr,Ti, Fe, Co, Ru, Au, Ni, and alloys thereof.

[0017] The method of making a head gimbal assembly in accordance withthe present invention comprises the step of mounting thus obtainedthin-film magnetic head to a gimbal. The method of making a hard diskdrive in accordance with the present invention comprises the step ofassembling the hard disk drive such that thus obtained thin-filmmagnetic head can read a magnetic signal recorded on a hard disk.Therefore, thus manufactured head gimbal assembly and hard disk drivecan eliminate the protrusion riding on the magnetoresistive film in theinsulating layer formed about the magnetoresistive film while preventingshort-circuit from occurring because of thus thinned insulating layer.As a consequence, the head gimbal assembly and hard disk drive attain ahigher reliability.

[0018] The present invention provides a thin-film magnetic headcomprising a magnetoresistive film having a magnetoresistance effect;lower and upper shield layers formed on respective sides of themagnetoresistive film by a ferromagnetic material; an insulating layerformed at least in a region, between the lower and upper shield layers,on a side opposite from the surface facing a recording medium in themagnetoresistive film; and a cover layer not covering the surface of themagnetoresistive film facing the upper shield layer but the surface ofthe insulating layer facing the upper shield layer.

[0019] Even if a part of the insulating layer rides on themagnetoresistive film in the thin-film magnetic head in accordance withthe present invention in a step of making the same, the upper coverlayer does not cover the surface of the magnetoresistive film on theupper shield layer side, whereby the protrusion can be eliminated byetching. Since the cover layer covers the insulating layer on the uppershield layer side, thus covered part is not etched. This can preventshort-circuit from occurring because of thinning the insulating layer.The cover layer may be formed by the materials mentioned above.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020] The present invention may be more readily described withreference to the accompanying drawings, in which:

[0021]FIG. 1 is a sectional view showing an embodiment of the thin-filmmagnetic head in accordance with the present invention;

[0022]FIG. 2 is a sectional view taken along the line II-II of FIG. 1;

[0023]FIGS. 3A to 3C are views showing manufacturing steps in anembodiment of the method of making a thin-film magnetic head inaccordance with the present invention;

[0024]FIGS. 4A to 4D are views showing manufacturing steps subsequent toFIG. 3C;

[0025]FIG. 5 is a view showing a sputtering apparatus for forming aninsulating layer and a cover layer;

[0026]FIG. 6 is a perspective view showing an embodiment of the headgimbal assembly and hard disk drive in accordance with the presentinvention;

[0027]FIGS. 7A to 7C are graphs showing an example of the presentinvention;

[0028]FIGS. 8A to 8C are views showing steps of making a conventionalthin-film magnetic head; and

[0029]FIGS. 9A to 9C are views showing conventional manufacturing stepssubsequent to FIG. 8C.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0030] In the following, preferred embodiments of the present inventionwill be explained in detail with reference to the accompanying drawings.Constituents identical to each other will be referred to with numeralsidentical to each other without repeating their overlappingexplanations.

[0031]FIG. 1 is a sectional view showing the thin-film magnetic head inaccordance with an embodiment of the present invention at apart slightlyinside of a surface (hereinafter referred to as “air bearing surface(ABS) S”) facing a recording medium, whereas FIG. 2 is a sectional viewtaken along the line II-II of FIG. 1. Words “upper” and “lower” used inthe explanation correspond to the upper and lower sides in FIG. 1,respectively.

[0032] This thin-film magnetic head 10 is a TMR head utilizing amagnetoresistance effect occurring at a tunnel junction. In thethin-film magnetic head 10, a lower shield layer 31 also acting as alower electrode, a lower metal layer 32, a pinning layer(antiferromagnetic layer) 33, a pinned layer 34, a tunnel barrier layer(intermediate layer) 35, a free layer 36, a first upper metal layer 37,a second upper metal layer 38, and an upper shield layer 39 also actingas an upper electrode are successively laminated on a support 11 in thisorder. The layers 33 to 36 constitute a TMR film (magnetoresistivefilm). As shown in FIG. 1, hard bias layers 41, 41 made of a hardmagnetic material are formed on both track width ends of the free layer36 by way of insulating layers 40, 40. Also, insulating layers 42, 42are formed between the hard bias layers 41, 41 and the second uppermetal layer 38.

[0033] The support 11 comprises a substrate 11 a made of AlTiC(Al₂O₃.TiC) and an undercoat layer 11 b formed thereon from anelectrically insulating material such as alumina (Al₂O₃) by a thicknessof about 1 μm to about 10 μm.

[0034] The lower shield layer 31 and the upper shield layer 39 are madeof a ferromagnetic material such as NiFe (Permalloy) and prevent the TMRdevice from sensing unnecessary external magnetic fields. Each of theshield layers 31, 39 has a thickness of about 1 μm to about 3 μm, forexample. The lower shield layer 31 also acts as an electrode asmentioned above, whereby an electron supplied from the lower shieldlayer 31 is transmitted to the upper shield layer 39, which acts as theupper electrode, by way of the lower metal layer 32, pinning layer 33,pinned layer 34, tunnel barrier layer 35, free layer 36, first uppermetal layer 37, and second upper metal layer 38. Namely, the sensecurrent flows in the film thickness direction of the TMR film.

[0035] The lower metal layer 32, first upper metal layer 37, and secondupper metal layer 38 are used for adjusting a read gap corresponding tothe recording density of a recording medium to a desirable value. Theupper metal layers 37, 38 also act to prevent the free layer 36 and thelike from oxidizing. Examples of materials forming the metal layers 32,37, 38 include Cu, Al, Au, Ta, NiCr, Ru, and Rh. Each metal layer mayhave a laminate structure.

[0036] The pinning layer 33 has a thickness of about 5 nm to about 30nm, and may be formed by an antiferromagnetic material such as PtMn, forexample, which can fix the magnetizing direction of the pinned layer 34by exchange coupling.

[0037] The pinned layer 34 has a thickness of about 1 nm to about 10 nm,and may be formed by a ferromagnetic material such as Fe, Co, Ni, orCoFe, for example. The magnetizing direction of the pinned layer 34 isfixed to the Y direction (or the direction opposite therefrom) in thedrawing by exchange coupling with the pinning layer 33.

[0038] The tunnel barrier layer 35 is a thin, nonmagnetic, insulatinglayer through which electrons can pass while keeping their spins bytunnel effect. The tunnel barrier layer 35 has a thickness of about 0.5nm to about 2 nm, and may be formed by an insulating material such asAl₂O₃, NiO, MgO, Ta₂O₅, or TiO₂, for example.

[0039] The free layer 36 changes the magnetizing direction under theinfluence of magnetic fields leaking from a recording medium such ashard disk. The free layer 36 has a thickness of about 1 nm to about 10nm, and may be formed by a ferromagnetic material such as Fe, Co, Ni,FeCo, FeCoNi, or CoZrNb, for example. Magnetic fluxes from the upperhard bias layers 41, 41 made of CoTa, CoCrPt, CoPt, or the like turn thefree layer 36 into a single domain extending along the X direction inthe drawing. As the air bearing surface S approaches a magnetizationshifting area of a hard disk, the magnetizing direction of the freelayer 36 shifts toward the positive or negative direction of the Y axis.When the magnetizing direction of the pinned layer 34 oriented in theY-axis direction and the magnetizing direction of the free layer 36coincide with each other, the current flowing through the tunnel barrierlayer 35 increases. When the magnetizing directions are opposite fromeach other, the current decreases.

[0040] The insulating layer 40 is formed by Al₂O₃ or the like, andprevents the current flowing through the free layer 36 or the like fromleaking toward the hard bias layer 41. The insulating layer 42 may alsobe formed by Al₂O₃ or the like, and prevents the current from leakingfrom the upper shield layer 39 to the hard bias layer 41.

[0041] As shown in FIG. 2, an insulating layer 45 made of Al₂O₃ or thelike is formed on the rear side of the TMR film 20 as seen from the airbearing surface S, i.e., in an area, between the lower shield layer 31and the upper shield layer 39, on the side of the TMR film 20 oppositefrom the air bearing surface S. The surface of the insulating layer 45on the upper shield layer 39 side is clad with a cover layer 50 made ofTa. The cover layer 50 has a thickness of about 0.5 nm to about 5 nm,and is formed so as not to cover the surface of the TMR film 20 on theupper shield layer 39 side. The effect of providing the cover layer 50will be explained later. Though the lower metal layer 32 and the secondupper metal layer 38 are disposed between the insulating layer 45 andthe respective shield layers 31, 39 in this embodiment, it is not alwaysnecessary to provide the metal layers 32, 38 in these areas. Namely, thecover layer 50 and the upper shield layer 39 may be in contact with eachother, whereas the insulating layer 45 and the lower shield layer 31 maybe in contact with each other.

[0042] With reference to FIGS. 3A to 3C and 4A to 4D showingmanufacturing steps, a method of making the thin-film magnetic head inaccordance with this embodiment will be explained. Though the metallayers 32, 37, 38 will be omitted from the explanation for easierunderstanding of the invention, these layers are formed in practice asnecessary.

[0043] First, as shown in FIG. 3A, a magnetic layer 19 to become a TMRfilm is formed on a lower shield layer 31 formed on a substrate 11 (notdepicted). Though the magnetic layer 19 has a multilayer structureincluding layers to become a pinning layer 33, a pinned layer 34, atunnel barrier layer 35, and a free layer 36 (see FIGS. 1 and 2), it isillustrated as a single layer for simplification. Subsequently, a resistlayer 60 is formed on the upper side of the magnetic layer 19. Theresist layer 60 is formed with a depressed undercut 60 a on each of bothsides (right and left sides in the drawing) of the bottom part (near theinterface with the magnetic layer 19). Forming such an undercut 60 amakes it easier for the resist layer 60 to carry out liftoff which willbe explained later. An example of methods of forming the undercut 60 acomprises the steps of coating the magnetic layer 19 with a layer ofpolymethyl glutarimide (PMGI) having a low molecular weight and thenapplying an electron beam resist onto this layer as described inJapanese Patent Publication No. HEI 7-6058. The undercut 60 a maybeformed by various known techniques such as those described in JapanesePatent No. 2973874 and No. 2922855.

[0044] Then, as shown in FIG. 3B, ion milling or the like is carried outwhile using the resist layer 60 as a mask, so as to pattern the magneticlayer 19. This yields a TMR film 20 having a desirable form. FIG. 3B andits subsequent drawings show only the part on the right side of adash-single-dot line l₁ in FIG. 3A.

[0045] Next, as shown in FIG. 3C, an insulating layer 45 of Al₂O₃ or thelike is formed by ion beam sputter deposition (IBSD) or the like, withwhich the surroundings of TMR film 20 eliminated by ion milling arefilled (so-called refilling) The insulating laser 45 secures insulationbetween the lower shield layer 31 and an upper shield layer 39 whichwill later be laminated. When laminating the insulating layer 45 bysputtering, an insulating layer 46 is also deposited on the resist layer60 in addition to the insulating layer 45 surrounding the TMR film 20.

[0046] Under the influence of the incident angle of particles at thetime of ion beam sputter deposition and the like, the insulating layer45 is formed with a protrusion 45 a riding on the TMR film 20. Further,a depression 45 b depressed as a shadow of the resist layer 60 (byso-called shadow effect) is formed between the protrusion 45 a and aflat part 45 c. As the depression 45 b is shallower, the TMR film 20 andthe upper shield layer 39 can be restrained from short-circuiting moreeffectively.

[0047] With reference to FIG. 5, an example of sputtering apparatus 80for realizing ion beam sputtering deposition (IBSD) will now beexplained. The sputtering apparatus 80 emits an ion beam from an ionbeam source 70 toward a target 72 provided with a material for formingthe insulating layer 45, thereby forming a film of the material of thetarget 72 onto the support 11 on a wafer stage 74. The incident angle θof the target material with respect to the support 11 can be adjustedappropriately by rotating the wafer stage 74 about its axis.

[0048] When forming the insulating layer 45 by such an apparatus, thefollowing technique is employed for decreasing the depression 45 b.Namely, in order to prevent colliding positions of sputtering particlesfrom being shadowed by the resist layer 60, particles are made incidenton the TMR film 20 while being inclined with respect to the normal ofthe TMR film 20 (i.e., in a direction allowing particles to be implantedinto the undercut 60 a of the resist layer 60, as indicated by blackarrows in FIG. 3C). This can reduce the depth of the depression 45 b.However, particles are also incident on the undercut 60 a, whereby theprotrusion 45 a formed on the TMR film 20 increases its size.

[0049] Subsequently, as shown in FIG. 4A, a cover layer 50 made of Ta isformed on the insulating layer 45 so as to cover the depression 45 b andexclude the protrusion 45 a while leaving the resist layer 60. As withthe insulating layer 45, the cover layer 50 can be formed by thesputtering apparatus shown in FIG. 5. Here, the angle of the wafer stage74 with respect to the target 72 is adjusted such that the incidentangle β of particles with respect to the surface direction of the TMRfilm 20 is greater than the incident angle θ at the time of forming theinsulating layer 45. Namely, the incident angle of particles at the timeof forming the cover layer 50 is closer to the normal of the TMR film 20than that at the time of forming the insulating layer 45. As a result,the cover layer 50 can be kept from covering the protrusion 45 a. At thetime of forming the cover layer 50, a deposited layer 51 is formed onthe resist layer 60.

[0050] Then, as shown in FIG. 4B, liftoff is carried out, so as toremove the resist layer 60 together with the insulating layer 46 anddeposited layer 51 deposited thereon. The protrusion 45 a of theinsulating layer 45 still remains after the liftoff. The protrusion 45 abecomes a cause of blocking a path of a sense current flowing into theTMR film 20.

[0051] Therefore, as shown in FIG. 4C, the protrusion 45 a on the TMRfilm 20 is eliminated by wet etching, for example. As an etchant,tetramethylammonium hydroxide (Shin-Etsu Resist SSFD-238N) may be used,for example. Here, in this embodiment, only the protrusion 45 a isetched, without etching the part of insulating layer 45 clad with thecover layer 50.

[0052] Subsequently, as shown in FIG. 4D, an upper shield layer 39 isformed by sputtering, for example, whereby a part functioning as areproducing section of the thin-film magnetic head 10 is obtained.Thereafter, a recording section including a thin-film coil and amagnetic pole is made on the reproducing section and, by way of knownprocessing operations of dicing the support into a plurality of bars,determining the MR height, and the like, the thin-film magnetic head 10is completed.

[0053] In thus obtained thin-film magnetic head 10, the part ofinsulating layer 45 clad with the cover layer 50 is not shaven whenetching the protrusion 45 a as mentioned above, whereby the upper shieldlayer 39 and the TMR film 20 can be prevented from short-circuitingbecause of thinning the insulating layer 45.

[0054] The cover layer 50 may be formed not only by Ta but also by SiO₂,AlN, or the like. The cover layer 50 may also be formed by a metalselected from the group consisting of Ta, Cr, Ti, Fe, Co, Ru, Au, Ni,and alloys thereof. When eliminating the protrusion 45 a of theinsulating layer 45 by wet etching, an etchant which etches theinsulating layer 45 without considerably etching the cover layer formedby the materials mentioned above is chosen. The protrusion 45 a may beeliminated by dry etching instead of wet etching as well.

[0055] A head gimbal assembly and hard disk drive using theabove-mentioned thin-film magnetic head 10 will now be explained whilereferring to their manufacturing methods.

[0056]FIG. 6 is a view showing a hard disk drive 1 equipped with thethin-film magnetic head 10. The hard disk drive 1 is assembled such thata head gimbal assembly 15 is actuated so as to allow the thin-filmmagnetic head 10 to record and reproduce magnetic information on arecording surface (upper face in FIG. 6) of a hard disk 2 rotating at ahigh speed. The head gimbal assembly 15 comprises a head slider 11(corresponding to the above-mentioned support) formed with the thin-filmmagnetic head 10, a gimbal 16 mounted with the head slider 11, and asuspension arm 17 connected to the gimbal 16. The head gimbal assembly15 is rotatable about a shaft 14 by a voice coil motor, for example.When the voice coil motor is rotated, the head slider 11 moves radiallyof the hard disk 2, i.e., in a direction traversing track lines.

[0057] Since such head gimbal assembly 15 and hard disk apparatus 1 usethe above-mentioned thin-film magnetic head 10, the protrusion 45 a inthe insulating layer 45 formed about the TMR film 20 can be eliminatedwhile short-circuit can be prevented from occurring because of thinningthe insulating layer 45. Therefore, the head gimbal assembly 15 and harddisk 1 attain a higher reliability.

[0058] With reference to FIGS. 7A to 7C, an example of the presentinvention will be explained. In the example, heights of the protrusion45 a, depression 45 b, and flat part 45 c were measured by AFM beforeand after wet etching. As the etchant, tetramethylammonium hydroxide(Shin-Etsu Resist SSFD-238N) was used. The cover layer 50 was formed byTa with a thickness of 0.5 nm. The insulating layer 45 was formed byAl₂O₃. As a comparative example, on the other hand, thicknesses of theparts 45 a to 45 c were measured in a case without the cover layer.

[0059] The ordinate in each of the graphs of FIGS. 7A to 7C indicatesthe vertical gap with reference to the upper face of the TMR film 20.FIGS. 7A to 7C show results of the protrusion 45 a, depression 45 b, andflat part 45 c, respectively. Results of the example provided with theTa cover layer are indicated by solid lines, whereas results of thecomparative example without the cover layer are indicated by brokenlines.

[0060] As shown in FIG. 7A, substantially all the protrusion 45 a waseliminated in each of the example and comparative example. As shown inFIG. 7B, the depression was deeply shaven by etching in the comparativeexample, whereas the cover layer 50 deterred the depression 45 b frombeing etched in the example. As shown in FIG. 7C, the cover layer 50also deterred the flat part 45 c from being etched. Thus, the exampleverified the effectiveness of providing the cover layer.

[0061] Though the invention achieved by the inventors is specificallyexplained with reference to the embodiment in the foregoing, the presentinvention is not restricted to the above-mentioned embodiment. Forexample, GMR (Giant MagnetoResistive) devices utilizing giantmagnetoresistance effect may be used in place of the TMR device. WhileGMR devices include CPP-GMR causing the sense current to flow in thefilm thickness direction and CIP-GMR causing the sense current to flowin the surface direction, the present invention is applicable to both ofthem. However, the present invention is more usefully employed in theCPP-GMR, since the sense current favorably flows when the protrusion onthe magnetoresistive film is eliminated.

[0062] The insulating layer and cover layer may also be formed by ionbeam deposition (IBD), in which the support is irradiated with ions madefrom a material for forming a film, instead of ion beam sputterdeposition (ISBD). Further, they may be formed by sputtering withoutusing ion beams. For providing the cover layer so as to eliminate theprotrusion, however, it is preferred that the cover layer be formed bysputtering utilizing an ion beam excellent in straightforwardness.

[0063] As explained in the foregoing, the present invention allows theprotrusion riding on the magnetoresistive film to be eliminated byetching. Also, since the insulating layer surrounding themagnetoresistive film is formed with the cover layer so as to excludethe protrusion, the part of insulating layer clad with the cover layeris not etched. This can prevent short-circuit from occurring because ofthinning the insulating layer.

[0064] The basic Japanese Application No. 2002-368601 filed on Dec. 19,2002 is hereby incorporated by reference.

What is claimed is:
 1. A method of making a thin-film magnetic headcomprising a magnetoresistive film; the method comprising the steps of:forming a magnetic layer to become the magnetoresistive film; forming aresist layer on an upper side of the magnetic layer; patterning themagnetic layer while using the resist layer as a mask so as to yield themagnetoresistive film; laminating an insulating layer about themagnetoresistive film; forming a cover layer on the insulating layer soas to exclude a protrusion riding on the magnetoresistive film in theinsulating layer; and etching the insulating layer formed with the coverlayer so as to eliminate the protrusion.
 2. A method of making thethin-film magnetic head according to claim 1, wherein a particle formingthe cover layer has a greater incident angle with respect to a surfacedirection of the magnetoresistive film than an incident angle of aparticle forming the insulating layer with respect to the surfacedirection of the magnetoresistive film.
 3. A method of making thethin-film magnetic head according to claim 1, wherein themagnetoresistive film is configured such that a sense current flows in afilm thickness direction.
 4. A method of making the thin-film magnetichead according to claim 1, wherein the cover layer is formed by SiO₂ orAlN.
 5. A method of making the thin-film magnetic head according toclaim 1, wherein the cover layer is formed by a metal selected from thegroup consisting of Ta, Cr, Ti, Fe, Co, Ru, Au, Ni, and alloys thereof.6. A method of making a head gimbal assembly comprising a thin-filmmagnetic head including a magnetoresistive film; the method forming thethin-film magnetic head by carrying out at least the steps of: forming amagnetic layer to become the magnetoresistive film; forming a resistlayer on an upper side of the magnetic layer; patterning the magneticlayer while using the resist layer as a mask so as to yield themagnetoresistive film; laminating an insulating layer about themagnetoresistive film; forming a cover layer on the insulating layer soas to exclude a protrusion riding on the magnetoresistive film in theinsulating layer; and etching the insulating layer formed with the coverlayer so as to eliminate the protrusion; the method further comprisingthe step of mounting the thin-film magnetic head to a gimbal.
 7. Amethod of making a hard disk drive comprising a thin-film magnetic headincluding a magnetoresistive film; the method forming the thin-filmmagnetic head by carrying out at least the steps of: forming a magneticlayer to become the magnetoresistive film; forming a resist layer on anupper side of the magnetic layer; patterning the magnetic layer whileusing the resist layer as a mask so as to yield the magnetoresistivefilm; laminating an insulating layer about the magnetoresistive film;forming a cover layer on the insulating layer so as to exclude aprotrusion riding on the magnetoresistive film in the insulating layer;and etching the insulating layer formed with the cover layer so as toeliminate the protrusion; the method further comprising the step ofassembling the hard disk drive such that the thin film magnetic head canread a magnetic signal recorded on a hard disk.
 8. A thin-film magnetichead comprising: a magnetoresistive film having a magnetoresistanceeffect; lower and upper shield layers formed on respective sides of themagnetoresistive film by a ferromagnetic material; an insulating layerformed at least in a region, between the lower and upper shield layers,on a side opposite from the surface facing a recording medium in themagnetoresistive film; and a cover layer not covering the surface of themagnetoresistive film facing the upper shield layer but the surface ofthe insulating layer facing the upper shield layer.